Safety fuel cutoff for heating appliances



Dec. 12, 1944. y f

R. MARTIN 2,365,092 SAFETY FUEL cUToFF FOR HFATNG APPLIANCES Filed Sept.2, 1941 4 sheets-sheet 1 L o .5 6 igll.

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SAFETY FUEL- CUTOFF FOR HEATING APPLIANCES Filed sept. 2, 1941 4Sheets-Sheet 2 Dec. l2, 1944. R. MARTIN SAFETY FUEL CUTOFF FOR' HEATINGAPPLIANCES Filed Sept. 2, 1941 4 sheebs-shee''l 3 Dec. 12, 1944. R.MARTIN vSAFETY FUEL CUTOFF FOR` HEATING APPLIANCES 1941 4 Sheets-Sheet 4Filed Sept. 2

l N V EN TOR /ussd/ /Vf BYML@ J ATTORN EY Patented Dec. 12,I 1944 UNITED"sTATss PATENT l orifice SAFETY FUEL `Curone Fon HEATING VAPPLIANCESRussell ltartin,y Wichita Kans., assignorl to The Coleman Lamp andSt'ov'e Company, Wichita, Kans., acorporaton of Kansas Application.september 2, 1941, serial No. 409,224l

solaires; (C1. 12e- 116) This invention vrelautes to a 'safety devicefor heaters yof the impe commonly .known :as floor `furneces fand .isdirected to ran improved structure over that disclosed in the Ambrose D.`Olds Patent No. 2,168,749 dated .August '8, i939.

A thermal limiting safety device to prevent, under certain conditions,.furnace overheating has long been used'. The application of thermallycontrolled safety devices 'to the more recently de'- velopedfflooiifurnsoe -is .however lcomparatively new, even thoughthis form `offurnace lends itself to `la f'sirnpler and more desirable form andcharactor or structure than has hitherto .been used.

'one metnodnovv honig 'used consists of a limit ing 'valve in the Ifuelline actuated by a 'thermal element located within the 'hot air sectionrnear the cop or the 'furnace This 'method requires the introduction ofian additional 'shut-olf valve iin the fuel line antifa `'consid'errableaccumulation of excess heat within the :furnace to effect operationwhich is undesirable.. This method `is fur'-v ther undesirable because`during normal operation it may cause 'the furnace to L:fluctuatecontinually in 'its burning rate., thus reducing lits effective elcency.

AAnother method isto locate the thermal element inthe cold air sectionofthe `furnace 'and depend on conduction `of heat from the warm airsection to operate' saine in `case `the furnace becomesoverheatedbecause 'of 'obstructed air now u tri-rough the furnace. This has notbeen satisfactory because of slow response. Another method similar 'tothe above, but dea recirculation or a'portion o'f the warmed air.tromtheuowa notving air of `the warm section into the down ard :flowingair'of the cold section. recirculation oi AWanmeol air is depenned uponto affect the operation of the thermal device which 'is located in thecold air section. This-method is undesirable because it permits aconsiderable `rec-irculation of warmed air' .vide a `furnace structurethat will cause a quicker and more substantial change 'of temperature toeffect quicker response of a thermal element to limit 'the vilov'v offuel to the burner in case the normal circulation Eof air through thefurnace is restricted by any unusual obstruction etiche-regis. terthrough which vcoo-l `air enters and Warm air is discharged.

Another ob-ject is to provide a furnace structure with `a secondaryupdraft section of Warmair in normal oper-ation 'and havingla reversecircu-` lation of hotter air in the 'eventof obstruction to the `airflow lat the grill,` thus providing a rapid temperature change toquickly actuate a thermal control `'element located at a point inthereverse fiowof hotter-air.

`Anctller 'object of 'this invention is to provide a cooler locationP`for the metering fue'l 'control valve `of .an 'oil burning fnoorfurn'ace, which location is adjacent 'the reverse hot'air now in theevent o'f register or grill obstruction, 'thus permitting thecombination f a thermal element With said metering valve to limit flow'of fuel to-'the burner,v

Another object oi this invention is toutilize the safety cut-off fuelvalve, which is designed to prevent excess fuel accumulation, y)and`iii/Ilich is a part of the fuel supply 'valve unit; i

Another'object olf this 'invention is 'to locate the thermal oontrol'inanormaily 'cool zohevvnich zone b'e'cc'mes v"oli'lickly heated by "ai'evcrse'air flow 'caused by obstructing 'the 'normalair how attheregister so that 'the therm'aioontroi oui'ckly limits now of fuel to'the burner vto hfevent 'une l`safe 'rise 'of temp'latiet th'efg'rill.

`ther objects of this invention are to 'provide a structure simple 'andinexpensive to manuface ture; and to secure quick 'positive acti-'on ofthe shut-orf valve 'by lonsy connections between the thermal elementsand the cut-off valve,

A further object of the invention is to 'provide a safety device'adapted tfor use in connection with the type of floor lfurnace employingahe'at transformer` described in my copending application, Serial No.386,595, Yfiled April 3, 1941. V

In accomplishing thesevand other objec'tsfof the invention, ashereinafterpointed out@ have provided improved structure, the preferredforms of `which are illustrated in the accompanying drawings, wherein: K

Fig. l is a vertical section through a liooi"` furnace of` the typeillustrated in -my above mentioned copending Aapplication equipped witha safety mechanism embodyingthe features of the present invention.

Fig. 2 is a perspective view of the constant level and control valve ofthe furnace equipped with a thermo-operated element arranged inaccordance with the present invention.

Fig. 3 is a longitudinal section through the control valve showing thetrip released and the fuel supply valve closed.

Fig. 4 is a fragmentary View of the thermoelement, particularlyillustrating the adjustable support for one end thereof.

Fig. 5 is a plan View of the constant level and control valve with thecover removed and showing the safety mechanism in partial section tobetter illustrate mounting of the thermoelement, the thermoelement beingshown as actuating the trip mechanism.

Fig. 6 is a cross-section on the line 6 6 of Fig. 3.

Fig. 7 is a partial plan view of the constant level and control valveshowing the trip in set position.

Fig. 8 is a side elevational view of the constant leveland controlvalve,part of the wall being broken away to illustrate position of the partswhen the trip is set.

Fig. 9 is an enlarged perspective view of the parts of the safetymechanism shown in disas` sembled spaced relation.

i Fig. 10 is a verticalsection through a furnace showing a vmodificationof the invention.

- Fig. '11 is a partial horizontal section through the furnace shown inFig. 10, and taken on the line II--I'L f.

^ Referring more in detail to the drawings:

I designates a oor furnace including a casing 2 which is ofsubstantially rectangular shape and includes vertical walls 3, a bottom4, and an open top 5.5- The walls 3 have laterally extending ange's 6 atthe. upper edges for suspendingly supporting the casing within anopening 'I of aiioor 8.( Theopen top of the casing, however, iscoveredwitha grill 9 having a marginal flange I0 engaging over theflanges 6 so that the upper surface thereofV is located at substantiallythe level of the floor 8.

`'Supported on suitable ledges Il in the bottom 4 is a frame I2,.carrying brackets I3 supporting a heater and burner unit I4substantially in the center of the casing and with the lower end spacedabove the bottom 4. In the illustrated instance the heater unit includesa combustion chamber I5, having walls II' forming heat radiating'surfaces I'I. Supported at the bottom of the combustion chamber isaburner or fire-pot I8 having connection vthrough a pipe I9 with aconstant level and control valve which is supported on the .frame I2adjacent` one ofthe side walls 3 of the casing 2. The constant levelvalve 20 is connected through a pipe 2| with a source of liquid fuelsupply, whereby fuel is supplied to the 'burner unit under control ofthe valve 20, asl later described. Supported on the brackets I3 is aninner jacket 22 having the walls thereof spaced inwardly of thecorrespond ing walls of the outer casing to provide a cold air sectionin the form of outer downdraft passages 23 and an air heating space 24containing the burner and heater'unit.

When the furnace is in operation, cool air from the` room movesdownwardly through the marginal portions of the grill and through thedown- Vdraft passages 23, under the lower edges of the jacket, andupwardly in heating relation with the walls of the combustion chamber,the heated air being discharged through the central portion of thegrill.

As disclosed in my copending application, the

hot gases resulting from combustion of the fuel circulate over the innersurfaces of the combustion chamber to heat the walls I6 thereof. Some ofthe heat is carried away from the walls of the heater unit by theupwardly moving stream of air, but a large portion of the heat radiatesthrough the upwardly moving stream of air and means is provided toabsorb the radiated heat so as to avoid heating of the downwardly movingstream of relatively cool air. AThis is effected by forming the jacket22 of an inner casing 25 and a heat transformer 26 which surrounds theheating unit. The walls of the heat transformer are spaced inwardly ofthe walls of the casing 25 and divides the air heating space 24 into aprimary hot air section consisting of passageways 21 and a secondarywarm air section consisting of passageways 28. These sections areinterconnected at their upper and lower ends and with the cold airsection at their lower ends as hereinafter described and in normaloperationthe air movement in boththe primary and secondary sections isupward with the cool air flowing into each at the lower ends.

The transformer 26 includes vertical walls 29 having their lower edges30 resting upon the brackets I3 and their upper edges 3I terminate shortof the walls 32 of the jacket to provide a material air space 33 underthe grill which connects the upper ends of the primary passageways. Theportions of the walls 32 which extend above the upper edges of thetransformerwalls slope inwardly, as shown in Fig. 1. The outer member 25of the jacket is carried by the member 26 by means of spacing brackets34 and 35 and the lower edges 36 terminate above the lower edges 30 ofthe member 26 to assure iiow of air from the downdraft passageways 23through the secondary updraft passageways 28, thereby providing apositive division of the air into the primary and secondary air streams,as shown by the arrows in Fig. 1. The transformer walls are thus locatedin path of the heat radiated from the heat unit and, being formed ofmaterial having high heat absorbing properties, absorb the radiated heatand prevent its absorption by the outer member 25 of the inner jacket.In the present instance, the outer member 25 of the inner jacket ispreferably formed of a heat reflecting material having a shiny innersurface 3'I to reect any heat that is reradiated from the transformerwalls. This arrangement is highly satisfactory and provides a moreefcient and higher velocity air circulation and results in a coolerfloor grill. However, it may happen that a rug or other obstruction maybe accidentally placed over the grill so that the circulation isobstructed, interfering with'normal flow of air through the furnace. Inthat event the hot, lighter air in the primary passage and therelatively cool and heavier air in the secondary passage tend toequalize pressures, thus setting up a circulation between the twonormally updraft passages. This causes reversal of air flow in thesecondary passage, bringing down hotter air from` the primary passage toactuate a thermostat which is utilized for effecting shut off of thefuel supply, as now to be described. 4

Since the constant level and control valve includes a safety shut-offvalve 2U and since this valve is located in the cool air moving throughthe downdraft passages 23 and into the secondary updraft passages 24 and28, I provide a thermo.

static element which is supported in the path of the cool vair and underthe secondary updraft acompte passageway adjacent lthe control land`constant level valve as shown in Fig. l. In this position the thermalelement remains inoperative as long as the furnace is operating undernormal temperatures but Whenever the normal flow of air is I obstructedand -a reverse' circulation lis effected downward through the secondarypassageways the down lio-w of hot air is brought Into direct con-tactwith the thermostatic 4element to assure actuation thereof for shutting*off ow of fuel. Thus the i-uel supply islsuspended when the ldownwardlydirected hot air strikes the thermal element and the `fuel. supply willremain shut olf until such 'a time that the 'thermostat cools downandthe valve is reset. "l

The valve 29 includes a casing '3B having a strainer chamber 39 on thebottom thereof vto which the fuel supply pipe 2l is connected. Formed inthe casing above the strainer vchamber isa float chamber 40 havingconnection with `the strainer chamber 39 Vthrough a `port 4l. The portill Lis formed in a tting 42 threaded in a boss at the bottom of .thecasing and has lateral outlets i3 to 'the iioat chamber. Reciprocable in'an axial bore '44 oi the ntting is a valvestem llli havf ing a conicalyend 119 to engage a seat encircling the port El. The upper end of thevalve stem carries 'an externally threaded sleeve Vlll that is iixeolthereon. Carried `by `the lower end of the sleeve 4l Vis a spring cap 48seating the upper end of a coil spring H9 which encircles a neck 5o ofthe iitting 42 and `has its lower end lbearing against a shoulder on thefitting to retain the valve in normally open position. The .spring 49 isrelatively light in action and Vis only oiy suflii' supported thereon isa yoke-.shaped bracket 56 comprising a transverse plate portion 5l,spaced vertical plate `portions 5S-A59, and foot portions -l engagingthe upper ends of the ribs and secured thereto by suitable yfasteningdevices 162.

.Carried by the side plate portions Elli and 59 of the .yoke-shapedbracket, at a point adjacent the collar 5l is a shaft B3pivotailymounting the arm l(it of a iioat that `is operable in the floatcham* ber responsive to the level ofv fuel 6B and which has a tongueportion 61 engaging the collar 5l so that when the float rises to the`level of the liquid to be carried `in the float chamber the tongueengages the collar and moves the valve stem toward closed position forthrottling inlet w of fuel according to the rate at which it is Ineteredto the burner'pot under setting of a regu`-v lating lvalve 68 `which 'islocated vWithin the `casinat and `has connection with the pipe I9. Theregu loting valve is manually adjusted by l.a stem 69 extending upwardlyin the downdraft 'passage- `way and having its upper end jcurnalled :ina bracket 10 projecting .from the side of -the inner jacket/asfshown inFig. l. v t

With the structure thus far described, it is obivous rthat the floatwill maintain a given level of fuel -in the float chamber to provide asubstantially Auniform hydrostatic head of liquid fuel to veffectcontrol of fuel flow to the burner with `themetering valve;

`respective sides yThe constant level and `"control valve has `a safetymechanism to shut oli the oil lflow in case the oilin the constant levelfloat chamber should, or .any cause, Arise fabove `a predeterminedlevel, as now to 'be described. lhztending transversely across the floatchamber 'and cooperating with thefend thereof opposite vthe inlet valveis a par tition TI termin-ating a v'slight distance -above the maximumliquid level to be carried in the iioat chamber so as yto `form a 'Weir:1 2 for overiiow of 'surplus fuel and to provide an overflow chamberT3. 'Operable 'in the overflow cl-i'amber 13 is a trip 'iioa-t 1:4`c'onorrninglin v'shape to the overovv chamber-and oi. substantially thesame 4size thereofso that a minimum amount of'overiiow'liquid willeffect; operationof the trip float. The iioat .TM has an ear '15pivotally connected by a pin TB with a lever '11. N'Iheleve'r Tl extendsover the top of the float E5 and is fixed on a cross-shaft 1TB havingits 4ends supported in the side plate portions 58 and 59 of theyoke-shaped bracket previously described. 'The lever l1 has an arm T9 onthe side of the shaft "I8 opposite the trip iioat "1-4 and formed onthe'lever at `the opposite side of the shaft "is ahook f8!) having ashoulder 8l tobe engagedbya trip 82.

'The vtrip B2 is best illustrated in Fig. 9, and includes ahorizontalplate `portion 83 Ahaving depending side flanges B4 and 85 provided withopenings B1B "topivotally'mount the trip on a shaft 81 which has its'end jcurnalled in the plate portions v58 land 59 ofthe bracket '5B onth-e side oi the valve stem opposite the 'shaft 18 pivoting the floatlever '11. Sleeved on the yshaft 81 is a 'coil spring 88, having `an arm"89 at one end engaging the bra-oketplate 59 and an arm `90 on itsopposite end bearingupon the plate portion 83 ofthe trip,

as shown in Fig. 7. Thus when the trip is dis engaged from the "hook '8Bofthe lever Tl, the spring 88 acts to 'bring ythe plate portion of thetrip into `engagement with the upper end ofthe valve stein 4:5 and forceit into `engagement with its seat. against-l vaction Aof the 'weakerspring 49 to vsluit oli iiovv of fuel to the float chamber. In

order to provide for resettingthe trip, the flange 86 thereof terminatesin an L-,shape'd lever 9i',

' havingV an 4arm "92 extending through a slot 33 inthe casing 3s. whenit is desired to set the tripgthe lever arm 92 Ais depressed againstaction of the spring 8B lto raise the 'plate portion of the trip from'engagement withthe valve stem to al'- low 'the 'weaker spring 49 tolift the valve stern, as shown .in Fig. 8. 'This movement oi the trip.lever raises the plate portion thereof so a relatively .narrow tongue'92# on the forward` end thereof rises under the hook Bl) and is inposition Ato be Lengaged thereby when the plate portion ofthe tripengages the arm T9 and `rocks the lever Il to bring the hook Sintoengagement with the .tongue ,as shown in Fig. 8. Initial movementy offlthe .lever Tl responsive to raising of the trip depresses the tripfloat i4 in theroverflow chamber '13 .so as to displace the liquidtherefroml Upon release ofthe trip lever the tongue .thereci' willengage on theshoulder 84' and the plate :portion of the trip lever willbe retained from en gagement with the upper Iend of the valve stem as4shown inFg. 8.

Ii for :some reason the float valve should fail toroperate, the liquidlevel will rise in the .neat chamber to the point where it overows .theweir l2 -into the overilowl chamber so that the over. ow fuel acts onthe trip float `14, raising the float vin the overflow Achamber andcausing the .lever 11 to rock on its supporting shaft 18 to effectrelease of the tongue 94 of the trip from engage ment with the hook 80.The spring 88 then comes into play to force the trip lever against theupper end of the valve stem and effect positive seating thereof to shutoff flow of liquid to the float chamber. The trip is readily reset bypushing on the arm 92 to again bring the tongue 94 of the trip inengagement with the hook 80 of the float arm 11. During engagement ofthe trip with the hook, the plate portion of the trip engages the arm 19and rocks the lever 11 downwardly so as to displace excess liquid fromthe overflow chamber back into the float chamber. Upon release of thearm, the spring 88 comes into play and moves the tongue of the trip intoengagement with the hook so that the trip is again supported and readyto be tripped in case the valve should fail to operate.

I also use the safety trip for suspending the fuel supply in case anarticle should be accidently placed over the grill, as now to bedescribed. Fixed to the exterior of the constant level and control valvecasing is a bracket 95 including a plate portion 96 fixed to the end ofthe valve casing by fastening devices, such as screws 91. Extending fromone edge of the plate and in spaced relation with the side wall of thecasing 38 nearest the secondary updraft passageway is an arm 98 having alaterally extending ear 99 which is provided with a slot |00cooperatingl .with a slot-like opening in the plate portion 96 to mounta thermoelement |02. The arm 98 of the bracket 91 is fixed to the casing38 by a screw |03 extending through an extension |04 of the arm. Theopening |0| is of greater width than the slot |00 to accommodateadjustment of the thermostatic element |02.

The thermostatic element comprises a bimetal blade arrangedsubstantially horizontally .with the ends and |06 projecting through theopenings |00 and |0| and so that the flat sides |01 thereof are inposition to be wiped by the air moving downwardly through the downdraftpassageway when the furnace is in normal operation and by the reverseflow of the air through the secondary passageway in case the outlet tothe furnace has been blocked by a rug or the like placed on the grill.The end |06 of the thermostat blade extending through tlie opening |0|is notched on the respective side edges thereof as indicated at |08,which notches are within the upper and lower edges |09 and ||0 of anopening in an adjusting plate ||2. The opening substantially conforms inwidth to the opening |0| and the plate ||2 is mounted on the plate 96 sothat the edge ||3 of the-opening cooperates with the edge ||4 of theopening |0| in limiting lateral movement of the notched end of thebi-,metal blade and to` adjust the blade relatively to the terminal endI5 of the shaft 18, Which end projects through a notch |6 in a side 0fthe casing as shown in Fig. 5. The plate ||2 is adjustably supported byfastening devices |1 extending through a slot ||8 in the plate ||2 andinto threaded openings ||9 of the plate portion 96 of the bracket 95.

The shaft 18 is retained in projected position so as to keep the hook 80thereof in alignment with the tongue 94 by a coil spring |20 sleeved onthe shaft and having one end engaging the hub |2| of the float lever 11and its other end engaging against the plate portion 59 of the yoke;like bracket 56. The shaft is thus yieldingly supported in projectedposition so that the end thereof is in position to be engaged by thethermostat blade when the blade is heated responsive to reversecirculation of air in the secondary draft passageway. When this occurs,the thermostat bows in the direction of the shaft, as shown in Fig. 5,to shift the shaft so as to carry the hook portion 80 of the float lever11 out of engagement with the tongue 94, whereupon the spring 88 comesinto play to cause the trip to move into engagement with the valve stemto seat the valve and interrupt flow of fuel in the same manner aswhen'the flow is interrupted responsive to overfiow of the fuel into theoverflow chamber. When the thermostat blade cools, the spring |20returns the shaft 18 to reposition the hook of the float leverrelatively to the tongue 94. The tongue 94 can then be reengaged withthe hook to set the trip by pressing on the arm 92.

Assuming that the furnace is in normal operation, air from the roommoves downwardly through the marginal edges of the grill 9, through thedowndraft passages 23, where a portion there of is directed upwardlythrough the secondary passages 28 and the rest through the primaryupdraft passageways 21. The air moving through the primary passageways21 picks up heat through contact with the hot surfaces of the combustionchamber |5 and the radiated heat which has been absorbed by thetransformer 26. The heat ab.- sorbed by the transformer 26 also heatsthe air passing through the secondary passages 28 which are relativelylarge to provide for unrestricted flow of air so that the outer walls 32of the jacket are kept in relatively cool condition and avoids heatingof the air in the downdraft passages. Therefore circulation of the airis maintained at higher velocity and the furnace operates moreefficiently and with a lower grill temperature.

Assuming that a rug is accidently thrown over the top of the grill 9 toblock or partially block flow of air therethrough, the hot air in theupdraft passageway 24 is diverted laterally so that it circulatesdownwardly through the secondary passageways and the hot air contactingthe thermoelement |02 produces warping thereof in the direction of theshaft 18 to effect shifting of the shaft 18 in a direction to move thehook 80 of the float lever 11 out of engagement with the tongue 94 onthe trip; When this occurs, thev spring 88 of the trip 82 forces theplate portion of the trip into seating engagement with the valve stem tostop flow of fuel to the burner pot I8. When the obstruction is removedand normal circulation is again set up in the furnace so'that thethermoelement |02 cools, the spring |20 returns the shaft 18 intoposition so that the hook 80 is in alignment with the tongue 94. Thetongue 94 may then be engaged with the hook by pressing on the arm 92.This is readily effected by extending a suitable wire or the likethrough one of the openings in the grill and engaging the arm 92. Thetrip is then supported against action of the spring 88 so that the stemof the valve is restored for actuation by the float whichregulates'level of liquid in the float chamber 40.

The form of the invention illustrated in Figs. 10 and 11 issubstantially the same as that just described, with the exception thatthe inner jacket |22 is of conventional floor furnace construction. Inthis instance the outer wall member |23 of the jacket is provided withan inner liner |24 spaced only a sufficient distance therefrom toprovide a dead air or insulating space |25 to insulate the outerdowndraft passage |26 from the updraft passage |21. In this case vthereis little upwardly through the secondary passages and to be contactedwith the hot air when hot air moves downwardly through said secondarypas.. sage, and an operating connection between the thermostat elementand said adjustable means -to cause actuation of said adjustable meansfor limiting ow of fuel when the thermostat element is subjected to flowof heated air moving downwardly through said secondary passage.

4. In a floor` furnace, an open top outer casing having side walls and abottom, a grill covering said open top of the outer casing, an open topinner casing having walls spaced inwardly of corresponding walls of theouter casing for forming downdraft and primary updraft passages incommunication with each other near the bottom of the casing whereby coolair to be heated moves downwardly through the downdraft passage andupwardly throughV the primary updraft passage, a heater unit in theprimary updraft passage for heating the air in the primary updraftpassage, means for-supplying fuel to the heater unit, adjustable meansin said fuel supply means for limiting ow of fuel to the heater unit, aduct ex- Cil tending substantially vertically of one of said walls ofthe inner casing and open at its upper end to the upper portion of theprimary updraft passage and open at its lower end to the downdraft andprimary updraft passages whereby relatively cool air from the downdraftpassage moves upwardly through said duct and hot air from the primaryupdraft passage moves downwardly through said duct when discharge ofheated air is blocked from the updraft passage through the grill, athermostat element adjacent to the lower end of said duct substantiallywhere the duct connects with the downdraft passage for contact with thecool air when the cool air moves upwardly through said duct and incontact with the hot air when hot air moves downwardly through saidduct, and an operating connection between the thermostat element andsaid adjustable means to cause actuation of said adjustable means forlimiting flow of fuel when the thermostat element is subjected to ow ofheated air moving downwardly through said duct.

RUSSELL MARTIN.

